import java.text.DecimalFormat;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int sum=0;
        for (int i=0;i<10;i++){
            int a=sc.nextInt();
            sum+=a;
        }
        double b=sum/10.000;
        System.out.printf("%.2f",b);
    }
}
